There are two basic spray bottle or spray can configurations: one employs a hand pump device to draw the liquid up the feed tube (commonly called, "dip tube") and then sprays the liquid out of the exit port; the second employs a pressurized gas to force the liquid up the dip tube and then sprays the contents out when the exit value is actuated. The use of hand pump bottles or pressurized cans to dispense a wide variety of substances such as glass cleaner, paint, perfume, etc. is widespread. Most of these containers have a single dip tube with an open end that extends into the liquid contents to serve as an entrance when the container is held in an upright position. However, when the container is inverted, the dip tube entrance is exposed to gas, and then only gas can be expelled from the container.
There are numerous patents which relate to the design of novel feed structures that can operate in either the fully upright position or the fully inverted position. The teachings of some of these patents are based on using valves that are dependent on the force of gravity to operate. One group (e.g. Grothoff U.S. Pat. No. 4,775,079) employs one or two balls that open or close flow passages depending on the orientation of the container utilizing the force of gravity. The other group (e.g. Ramsey U.S. Pat. No. 3,733,013 employs slugs that open or close flow passages that also utilize the force of gravity. When the bottle is partially inverted so that the open end of the dip tube is not in contact with liquid, but the component of the force of gravity is insufficient to move the ball or slug to unseat the port, the system will expel gas rather than liquid. Because of the difficulty of obtaining an acceptable gas seal with a ball or slug which is held in position by gravity, none of these patents teaches a concept that will operate consistently at orientations between the fully upright or the fully inverted positions. An additional disadvantage of these concepts is the relatively high cost of the valve.
Another group of patents describes dip tube configurations that will pass some types of fluids but not others. These concepts do not require valves to control the flow into the dip tube. One type is for dispensing a three-phase system wherein phase I is a gaseous propellant and phases II and III are two immiscible liquids. In these patents, a dip tube is described that allows one phase of material to pass but prevents the entrance of another phase. In particular, Pong et al (U.S. Pat. No. 4,418,846) describes two immiscible liquids, one of which is a lipophilic phase and the other is a non-lipophilic phase. The dip tube has an open end through which the non-lipophilic phase flows and a tubular structure formed of a lipophilic material having multi-directional pores through which the lipophilic phase flows. The lipophilic liquid is thereby combined with the non-lipophilic liquid and the combination is passed through the valve means and is dispensed through the valve. Pong et al (U.S. Pat. No. 4,398,654) describes a similar dip tube with an open end through which can pass an aqueous liquid and a tubular structure through which a non-aqueous liquid will flow. There are no claims or description of any inverted operation since these structures operate satisfactorily only if the container is in an upright position. They are mentioned here only because the structures pass one type of fluid but will not pass another.
Nandagiri U.S. Pat. No. 4,546,905 describes an aerosol dispensing device having a porous dip tube that also is closed with the same porous material at the bottom entrance that, in a conventional dip tube, is normally open. The specification contains only a vague description of the operation of the device since it does not include any examples of pore sizes or any method for determining the desired pore size. Also it makes no mention of the percentage of pores (i.e. the ratio of void area to the solid wall area) or the critical dimensions of the porous dip tube (i.e. length, diameter, wall thickness). Since the specification is devoid of any teachings for determining these properties, it is not possible to evaluate the concept precisely. However, it is possible to determine the general performance that could be expected from the dip tube that is fabricated with porous material and that has the bottom entrance also covered with the porous material. While the system may operated satisfactory in the upright and inverted positions when the container is completely full of liquid, it will dispense only gas in either the upright or the invert position when the container is only partially full of liquid. The result is that a large percentage of the original contents of the container can not be dispensed. This problem, very likely, is the reason that the invention has not been in commercial use. The cause and the solution to this problem will be made clear from the teachings of this specification.
There is yet another patent which is of interest in the teaching of the present patent. This patent (Naess U.S. Pat. No. 4,529,414) describes a design for the separation of gas from a liquid in a flow system having at least one permeable blocking layer so arranged along the length of the pipe that the liquid remains on the underside of the blocking medium. This system relies on surface tension and capillary forces to separate the gas from the liquid. It is of interest only because it employs surface tension forces to separate the gas and liquid since it is not related to spray bottles in any manner.
There are several patents for propellant feed systems that operate in zero or near zero gravity fields. Ellion et al (U.S. Pat. No. 4,272,257) is typical of these patents which rely on surface tension to allow liquid to flow and prevent the discharge of gas. Ellion describes a system that has numerous entrances all of which are covered with porous material. A summary article for these zero-gravity rocket motor feed systems is given in the Journal of Spacecraft and Rockets Vol. 8 No. 2 Feb. 1971 pages 83-88 by S. Debrok. Although these patents employ surface tension devices to prevent gas from leaving the container, none of them relates to spray bottles that operate in a gravity field and they all require multiple, complex, expensive porous material to cover all of the numerous entrances.
It is a principal object of this invention to provide a feed system for a hand held spray bottle that is usable when the bottle is at any orientation.
It is another object of this invention to provide a feed system that operates automatically without requiring manipulation on the part of the user.
It is yet another object of this invention to be able to operate this container feed system on earth and consequently in a gravity field or at any gravity level above or below earth's gravity level.
It is still another object of this invention to have no moving parts which would increase the complexity or cost of the feed system.
It is yet another object of this invention to have the capability to dispense the entire contents of the container.
It is a further object of this invention to provide a feed system that requires only a single porous entrance port in addition to the open dip tube entrance port.
It is still another object of this invention to provide a simple, inexpensive feed system that requires little or no added assembly steps over those required for the existing conventional spray bottles.
Other objects and advantages of this invention will become apparent from the following specifications and appended drawings.